1. Field of the Invention
The present invention relates to a method of manufacturing seats used in vehicles such as automobiles, furniture, etc.
2. Description of the Prior Art
In a method of manufacturing an integrally-covered molding seat, a hot-melt adhesive is sometimes used to bond a pad member and a cover member. Known hot-melt adhesives include spreadable adhesives (reactive hot-melt type and the like) and hot-melt sheets (film type and the like).
A spreadable liquid hot-melt adhesive, such as the one described in Jpn. Pat. Appln. KOKAI Publication No. 3-68391(prior art example 1), is cooled after it is spread on a pad member or a cover member.
Thereafter, the pad member and the cover member are superposed and pressurized, and the hot-melt adhesive is heated to be melted with hot air or high-temperature steam. After the adhesive is cooled, the members are released from the mold.
As is described in Jpn. Pat. Appln. KOKAI Publication No. 61-176387 (prior art example 2), on the other hand, a sheet-type hot-melt adhesive or hot-melt sheet is put on the upper surface of a pad member, and a cover member is superposed on the resulting structure. The pad member and the cover member are pressurized and heated with hot air or high-temperature steam so that the hot-melt sheet is melted. Thereafter, the resulting structure is cooled and released from the mold. In the case where the hot-melt sheet of this type is put on the cover member, the hot-melt sheet is usually laminated beforehand to the cover member that is cut and sewn.
In either of the prior art examples 1 and 2, the hot-melt adhesive is heated as it is insufflated with hot air or high-temperature steam from the outside of the cover member or from the inside of the pad member, with the two members superposed.
In the case where the hot-melt adhesive is heated with the hot air from the outside of the cover member, however, the surface of the cover member, if made of a raised fabric, is flattened as it is heated and pressurized. Thus, the surface suffers deterioration in external appearance, such as whitening. In the case where the hot-melt adhesive is heated with the hot air from the inside of the pad member, on the other hand, the thermal efficiency is very poor, and besides, the pad member may possibly be degraded by heat. Further, heating and cooling devices must be incorporated into a mold for pressurizing the pad member and the cover member, so that the construction of the mold is complicated.
In the prior art examples 1 and 2, the hot-melt adhesive is melted by heating the pad member and the cover member that are pressurized against each other. Therefore, the hot-melt adhesive is bound on the interface between the pad member and the cover member as it is melted. Thus, the melted hot-melt adhesive becomes a continuous film or net between the pad member and the cover member as it hardens. Thus, the surface portion of the cooled (or bonded) cover member is too rigid to be pleasant to the touch.